Re: [PATCH for-7.2 v3 0/3] rtl8139: honor large send MSS value

[Stefan Hajnoczi]

On Thu, Nov 17, 2022 at 11:55:51AM -0500, Stefan Hajnoczi wrote:
> v3:
> - Add Patch 1 to avoid clobbering tx descriptor bits
> - Add Patch 2 to avoid confusing tx command modes
> - Exclude IP and TCP headers from large send MSS value
> 
> The rtl8139 large send offload currently does not honor the MSS value provided
> by the driver. This is a problem especially when the MTU is small because IP
> fragmentation occurs and leads to poor performance.
> 
> These patches make use of the large send MSS value.
> 
> I have done basic testing by running the following Python code inside the
> guest:
> 
>   import socket
>   s = socket.socket()
>   s.connect(('10.0.2.2', 1234))
>   buf = b'A' * 4096
>   s.send(buf)
> 
> The device sees a 4150 byte tx descriptor that results in the transmission of 
> 3
> Ethernet frames with sizes of 1514, 1514, and 1230 bytes when the large send
> MSS value is 1460 bytes.
> 
> Stefan Hajnoczi (3):
>   rtl8139: avoid clobbering tx descriptor bits
>   rtl8139: keep Tx command mode 0 and 1 separate
>   rtl8139: honor large send MSS value
> 
>  hw/net/rtl8139.c | 47 ++++++++++++++++++++++++-----------------------
>  1 file changed, 24 insertions(+), 23 deletions(-)
> 
> -- 
> 2.38.1
> 

Thanks, applied to qemu.git/master!

Stefan

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